| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| package org.apache.samza.application; |
| |
| import java.util.Optional; |
| import org.apache.commons.lang3.StringUtils; |
| import org.apache.samza.config.ApplicationConfig; |
| import org.apache.samza.config.Config; |
| import org.apache.samza.config.ConfigException; |
| import org.apache.samza.config.TaskConfig; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| |
| /** |
| * Util class to create {@link SamzaApplication} from the configuration. |
| */ |
| public class ApplicationUtil { |
| private static final Logger LOG = LoggerFactory.getLogger(ApplicationUtil.class); |
| |
| /** |
| * Creates the {@link SamzaApplication} object from the task or application class name specified in {@code config} |
| * |
| * @param config the configuration of the application |
| * @return the {@link SamzaApplication} object |
| */ |
| public static SamzaApplication fromConfig(Config config) { |
| |
| String appClassName = new ApplicationConfig(config).getAppClass(); |
| if (StringUtils.isNotBlank(appClassName)) { |
| // app.class is configured |
| try { |
| Class<SamzaApplication> appClass = (Class<SamzaApplication>) Class.forName(appClassName); |
| if (StreamApplication.class.isAssignableFrom(appClass) || TaskApplication.class.isAssignableFrom(appClass)) { |
| return appClass.newInstance(); |
| } |
| } catch (IllegalAccessException | InstantiationException | ClassNotFoundException e) { |
| throw new ConfigException(String.format("Loading app.class %s failed. The user application has to implement " |
| + "StreamApplication or TaskApplication.", appClassName), e); |
| } |
| } |
| // no app.class defined. It has to be a legacy application with task.class configuration |
| TaskConfig taskConfig = new TaskConfig(config); |
| Optional<String> taskClassOption = taskConfig.getTaskClass(); |
| if (!taskClassOption.isPresent() || StringUtils.isBlank(taskClassOption.get())) { |
| // no task.class defined either. This is wrong. |
| throw new ConfigException("Legacy task applications must set a non-empty task.class in configuration."); |
| } |
| return new LegacyTaskApplication(taskClassOption.get()); |
| } |
| } |